The present invention relates to devices for controlling the flow rate in a conduit and particularly to flow control of water to the inlet of a household appliance such as a dishwasher, clothes washer, or refrigerator ice maker. In providing flow rate control to household appliances connected to municipal water supplies, it is desired to provide a generally constant flow rate to the appliance inlet in the face of wide variations in the water supply pressure. Various types of flow control devices have been employed for this purpose; and, a particularly well known device is an elastomeric washer which deforms resiliently under increasing supply pressure to restrict the flow orifice size, thereby maintaining a constant flow rate.
However, in providing flow control to the water inlet of an appliance, problems have been experienced in excessive noise, where the restrictions of the flow control device have produced cavitation. In cases where the flow control is applied at the inlet of an electrically operated water inlet valve, the noise problem has been particularly exacerbated by the flow cavitation causing resonant vibration of the surrounding valve body structure. This problem has been particularly troublesome in appliance water inlet valves having body structure rigidly secured to a surrounding metal frame or cabinet of the appliance.
Where an appliance water inlet flow control device is required to control substantial restriction to accommodate relatively high water supply pressures for maintaining a constant flow rate to the appliance inlet, severe high frequency vibration has been encountered as cavitation occurred at the flow control device; and, the resulting noise is perceived to be quite objectionable to the appliance user. It has thus been desired to find an inexpensive way or means of controlling the noise associated with flow control devices employed for controlling the rate of flow at the inlet of an appliance.